JPS5818845A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To enable an accurate landing condition to be maintained by forming an asymmetrical electron lens so that the line connecting the centers of a pair of electron beam passing holes becomes slant from the beam-orbit axis, and changing the degree of the slant of the above line in accordance with the thermal deformations of shadow masks. CONSTITUTION:Penetrating hole centers 7 and 11 of two shadow masks are constituted so that a penetrating-hole-center axial line 12 connecting the centers 7 and 11 is not perpendicular to a fluorescent screen, and so that the line 12 is slant from the incidence orbit axis of an electron beam 5. Since an anode voltage (Eb) is larger than a sub-focus voltage (Vg), an incoming electron beam 5 is curved along the direction of the line 12. Due to thermal deformation of the shadow masks caused by the electron beam 5, the electron beam 5 located on a given phosphor 3 moves to the right, and at the same time, a distance (gM) changes. As the result, a correction which is almost euqal to the degree of the movement of the electron beam 5 and is in the reverse direction to the above movement can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color cathode ray tube having a plurality of color selection electrodes or shadow masks.

In the color cathode ray tube 1c, a color selection electrode, that is, a shadow mask, is used as the electron gun in order to accurately irradiate the three electron beams from the electron gun onto the phosphors each having a predetermined emission color to produce the correct color. It is provided between the fluorescent surface and the fluorescent surface. This shadow mask has a large number of through holes for passing the electron beam, and a mask portion for cutting off the electron beam.
That is, a portion other than the through hole is provided, and a very high degree of shape accuracy is required in order to obtain an accurate landing shape W of the electron beam. A very thin metal plate is usually used for the shadow mask VC, and through holes are formed by etching, etc.'
However, in general, the thinner the gold plate is, the higher the accuracy can be obtained. However, significantly more than half of the electron beam is irradiated onto the part of the shadow mask outside the hole, which heats up the shadow mask, causing thermal deformation and causing it to deviate from the normal landing state. The thinner the shadow mask is, the greater this phenomenon becomes. As a solution to this inconvenience,
For example, a shadow mask is fixed to a panel glass via a bimetal to correct displacement of the shadow mask due to heating. However, although this method is effective for correcting the displacement of the entire mask, it is not a solution to the thermal deformation caused by local electron beam incidence. Therefore, as a solution to this problem, it would be possible to increase the thickness of the shadow mask, but this would conversely end up lowering the processing accuracy of the electron beam holes.

In addition, measures such as making the surface of the aluminum metal back facing the fluorescent light further black may also be used to improve the heat radiation effect by radiating the heat generated by the shadow mask towards the panel lath. None of these methods is a fundamental solution to maintaining accurate landing of the electron beam, but Jilt/-a
It is something.

Furthermore, Japanese Patent Publication No. 55-2698 discloses a technique for preventing landing deterioration due to thermal deformation by using a double mask with through holes arranged along the orbital axis of the electron beam.

However, in this method, the m2 mask simply shields the electron beam tS, and even if different potentials are applied to each double-structured mask, if the shielding mask is thermally deformed, the electric field will change. This has the drawback of causing the electron beam to shift and severely deteriorating the landing.

The present invention has been made in view of the above points, and uses a plurality of shadow masks. In particular, the central axis of the through hole connecting the centers of each pair of corresponding electron beam transmission holes in the peripheral area is relative to the electron beam orbit axis. By configuring it to have an inclination,
An asymmetric electron lens is formed in the through hole, and the inclination i is adjusted according to thermal deformation of the entire shadow mask of the asymmetric electron lens.
The object of the present invention is to provide a color cathode ray tube configured to vary l and maintain an accurate landing state.

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram showing the basic structure of a color cathode ray tube according to the present invention, particularly in the vicinity of a shadow mask. In Figure 1, the glass face plate of a color cathode ray tube) (1
) is formed with a fluorescent surface (2), and the fluorescent surface (2) has a fluorescent material (3) that emits light in each color and a black light absorber layer (4) on the remaining surface t-a. It consists of This fluorescent surface (2
) and an electron gun (not shown) that emits a plurality of electron beams, and an electron beam (5) is located close to the fluorescent surface (2).
A shadow mask (6) is provided to properly illuminate a corresponding predetermined phosphor (3). Furthermore, a second shadow mask (IQ) is placed close to the electron gun side of this shadow mask (6), and these two shadow masks (
6) and 0 (different potentials are applied to IK.
The corresponding through-hole centers (7) and 01) of the two shadow masks are arranged such that the through-hole axes (8) and (9) perpendicular to the phosphor surface are different, that is, through-hole centers (7) and 01
) is configured so that the central axis a2 of the through hole is non-perpendicular to the fluorescent surface, and the central axis a3 of the through hole is also configured to be non-parallel to the incident trajectory axis of the electron beam (5). ,
That is, it is configured to have an inclination. In the cathode ray tube having the above-mentioned array configuration and the quadrature angle δ, a voltage is applied to the anode voltage Eb) and the subfocus voltage Vg, so that the incident electron beam (5
) is bent along the direction of the hole center axis SaW connecting the hole center (7) of the shadow mask (6) and the hole center '-aυ of the second shadow mask QG. At this time, the amount of change # in the angle between the incident orbital axis of the electron beam (5) and the center axis waas of the through hole is approximately expressed as ΔD Eb θ″″=KX d×interval. However, KH Shadow Mask (6),! :
A constant determined by the distance tM from the second shadow mask Qa, the anode voltage gb, and the subfocus voltage Vg, and D is the through-hole diameter of the second shadow mask (6) and the second shadow mask (II).

Now, suppose that the shadow mask is thermally deformed by the electron beam (5) emitted from the electron gun. The electron beam moves to the right in Figure 1, and at the same time, the distance tMdi between the shadow mask (6) and the second shadow mask a increases, and the negative value of the constant increases. When it gets bigger, the electron beam (
5) If the deflection angle 0 between the through-hole central axis α and the incident orbital axis is too large, thermal deformation of the shadow mask will cause the electron beam (51 force) to be corrected in the opposite direction by an amount approximately equivalent to the amount of movement. You can get the amount.

Figures 2 to 4 show embodiments of the present invention.
Elements that are common to the figures are designated by the same number.

That is, Figure 2 shows the case where the present invention is applied to a shadow mask with a circular hole shape, Figure M3 shows the case where the present invention is applied to a rectangular shadow mask, and Figure 4 shows the case where the present invention is applied to a shadow mask with a circular hole shape. This is a so-called aperture grill shape in which an unbroken metal wire is stretched along a straight line.
This is a case where the present invention is applied to a Yado mask, and in either case, its basic structure and operation are the same as those shown in FIG. Further, it is possible to use a plurality of shadow masks in combination with hole-shaped shadow masks shown in FIGS. 2 to 4.

As described above, according to the present invention, a color cathode ray tube having accurate electron beam randomization can be obtained even by thermal deformation of a shadow mask.

[Brief explanation of the drawing]

FIG. 1 is a partial schematic diagram showing the basic configuration of a color cathode ray tube according to the present invention, particularly in the vicinity of a shadow mask, and FIGS. 2 to 4 are partial schematic diagrams showing embodiments of the present invention. (1)... Glass face plate (2)... Firefly f, m (3)... Fluorescent material (4)... Light absorber layer (5)... Electron beam (6), Ql...
・Shadow mask (7), Qυ... Clear hole center +
81. (9)...Through-hole axis a...Through-hole center axis (7317) Representative Patent Attorney Noriyuki Chika (and one other person) Figure 2 Figure 4 Figure 3

Claims (1)

[Claims] In a color cathode ray tube in which a plurality of shadow masks are arranged between a fluorescent surface and an electron gun, and different potentials are applied to the shadow masks, corresponding pairs of electron beam transmission holes in the periphery of the plurality of shadow masks are arranged. A color cathode ray tube characterized in that a central axis of the through hole connecting the centers of each of the holes has an inclination with respect to a trajectory axis of an electron beam incident on the pair of electron beam transmission holes of the shadow mask.